Eventually, Naruto catches up to Sasuke at the Valley of the End, asking Sasuke to return with him to Konoha. Sasuke merely rebuffs Naruto, who angrily tells him that the Sasuke Recovery Team risked their lives just to bring him back to Konoha, although Sasuke is indifferent to their actions. Infuriated at Sasuke's callous demeanour, Naruto recalls how Chōji took on Jirōbō in order to give the others a chance to retrieve Sasuke and how Neji did the same when he decided to battleKidōmaru single-handedly, reminding Naruto that Sasuke was lost in the darkness. Although they managed to retrieve the barrel containing Sasuke, an incensed Sakon activated his cursed seal and pursued them. Kiba and Akamaru, along with Sakon and Ukon, ended up plummeting off a cliff, leaving Naruto and Shikamaru to deal with Tayuya. However, Kimimaro, one of Orochimaru's loyal servants, stole the barrel containing Sasuke and fled; Shikamaru decided to deal with Tayuya himself and instructed Naruto to follow Kimimaro. As Naruto caught up to his foe in a meadow, Sasuke emerged from his barrier and laughed at his new power, before running away. Kimimaro decided to take advantage of Naruto's distraction in order to kill him, only for him to be attacked by Rock Lee, who had arrived in the nick of time to allow Naruto to chase after Sasuke.

Gritting his teeth as he recalls all the potential sacrifices their fellow comrades made, Naruto lunges towards Sasuke and punches him across the face, although Sasuke kicks him away. Landing in the water below, Naruto realises that Sasuke intends to kill him. He attempts to reach out to his teammate, asking if the memories of Team 7 meant nothing to him, but Sasuke replies that one thing made it worthwhile — his friendship with Naruto. Wishing to kill Naruto in order to obtain the Mangekyō Sharingan, Sasuke rushes towards him with his Chidori as Naruto creates a shadow clone and counters the attack with his Rasengan. The clash sends the two of them flying in opposite directions, with Sasuke being amazed that Naruto was able to negate the effects of his Chidori. Sasuke activates his cursed seal as he once more charges towards Naruto with his Chidori, this time succeeding in his attack, puncturing Naruto's right lung.

However, Naruto is enveloped in the chakra of the Nine-Tails and is able to fight back. Shocked at this new display of power, Sasuke asks Naruto what he is, only for the latter to claim that he is his friend. Naruto viciously attacks Sasuke before pinning him to a rock while Sasuke shouts that Naruto would never understand the suffering he is enduring as he never had parents or siblings and asks why Naruto would go so far for him. Naruto replies that while all of that is true, he views Sasuke as the closest thing he has to a brother and thus is fighting to preserve that bond. Accepting Naruto as his equal, Sasuke puts on his forehead protector. As Naruto enters into his one-tailed form, Sasuke accesses the second stage of his cursed seal and undergoes a transformation, gaining two giant wings as his skin becomes darker and his hair grows out. As the members of the Sasuke Recovery Team are saved, Sasuke prepares an enhanced Chidori while Naruto forms an augmented Rasengan, and the two collide.

Sasuke emerges victorious from the battle as Naruto is rendered unconscious. Deciding not to kill Naruto and to obtain power in his own way, Sasuke walks away from the Valley and finds his way to Otogakure, demanding Orochimaru to give him power. Meanwhile, Kakashi and Pakkun locate Naruto and bring him back home, as Naruto realises that he has failed in his mission and mentally mutters an apology to Sakura.